Vehicle monitor

ABSTRACT

In accordance with the equipment of the present invention, the communication over the entire region of a wide working site can be performed without a cost increase due to the installation of auxiliary equipment, the mutual control of vehicles can be performed with a light burden on a monitoring station without sacrificing safety, and when a failure occurs to transmission/reception equipment, the failure can be quickly and accurately confirmed, and accordingly the abnormality can be quickly and properly dealt with. In the of the present invention, first transmission/reception system for transmitting/receiving at least command data between the monitoring station and a plurality of vehicles via a first communication system which enables wireless communication over the distances between the monitoring station and the vehicles is provided in the monitoring station and the vehicles respectively. Second transmission/reception system for transmitting/receiving position data measured by vehicle position measurement between the vehicles via a second communication system which enables wireless communication over the distances between the vehicles and enables faster data transmission/reception than the first communication system is provided in the vehicles respectively. The respective vehicles judge the approach of another vehicle by transmitting position data between the vehicles via the second transmission/reception system provided in the vehicles respectively, so that the mutual position relationships between the vehicles can be monitored.

TECHNICAL FIELD

The present invention relates to a vehicle monitor comprising aplurality of vehicles having vehicle position measurement means formeasuring the respective vehicle position and a monitor station whichtransmits command data for instructing traveling to the plurality ofvehicles.

BACKGROUND ART

In order to manage the movement of a plurality of unmanned vehicles,unmanned dump trucks for example, for transporting soil in a wideworking site, such as a quarry and mine, a monitoring station isestablished as a ground station and a vehicle monitoring system isstructured such that this monitoring station manages and monitors theseunmanned vehicles comprehensively.

This vehicle monitoring system has a transmission/reception equipment(e.g. VHF system) for performing long distance wireless communicationbetween the monitoring station and the plurality of vehicles, andvarious data, including the position data of the respective vehicleswhich were measured, is transmitted to the monitoring station inextremely short cycles (e.g. every one second), so that the monitoringstation can monitor each vehicle knowing the accurate position of therespective vehicles.

The monitoring station which received the position data from a vehicletransmits data to notify reception so that each vehicle can confirm theoccurrence of failure of its transmission/reception equipment.

Recently, however, it is becoming necessary to monitor many vehicles(50-100 vehicles) which travel very long distances (approx. 10 km) inmany traveling courses, where information to be handled is dramaticallyincreasing.

To handle this status, it is necessary to install transmission/receptionequipment which can perform fast wireless communication in a wide range(long distance).

According to currently available technology, the following are the twotypes of communication systems which can practically support suchmonitoring of vehicles.

1) VHF, UHF

2) SS (spread spectrum system) wireless communication

However, if the 1) VHF or UHF system is applied to the above mentionedvehicle monitoring system, the communication system, which allows longdistance communication (10 km-20 km), can provide communication in thewhole region of a wide working site, but the current positions of manyvehicles cannot be constantly known since the communication speed isslow (9600 bps). In other words, a large volume of data is transmittedfrom many vehicles to the monitoring station. And since thecommunication system with a slow communication speed handles this largevolume of communication information, communication lines jam, the loadon the communication lines increases, and the management and monitoringof the vehicles become virtually impossible.

If the 2) SS wireless communication system is applied to the vehiclemonitoring system, the communication system which allows high-speedcommunication (256 Kbps) can transmit an extremely large volume ofinformation at high-speed, but cannot provide communication in the wholeregion of a wide working site, which is now becoming increasingly wider,since the propagation distance of radio waves is short (100 m-1 Km).

Also, in order to provide communication in the whole region of a wideworking site by SS wireless communication, such auxiliary equipment asradio stations must be installed at various locations of the workingsite to compensate for the insufficient propagation distance of radiowaves. This increases cost for initial investment and maintenance, whichlessens the practicality of this system.

Conventionally the communication system in the above 1) has beenadopted, and in order to compensate for the management of vehiclesperformed by the monitoring station, an obstacle sensor is installed oneach vehicle, so that this sensor confirms the presence of othervehicles to prevent collision. However such a system which preventscollision by such a sensor alone has safety problems, and is notdesirable. This is because 100% collision cannot be prevented when manyvehicles pass cross sections or pass another vehicle.

In both the communication systems of the above 1) and 2), the monitoringstation controls all vehicles, therefore the problem of excessive loadon the monitoring station remains unsolved.

Further, when many vehicles transmit data to the monitoring station, themonitoring station transmits data for notifying the reception of thedata back to the many vehicles so that each vehicle confirms the failureof the transmission/reception equipment of the respective vehicle, asmentioned above, but if this method is implemented by the communicationmethod in the above 1), the monitoring station cannot always transmitthe data for notifying the reception of the data back to many vehiclesdue to the slow communication speed of the system, and as a result, thevehicles cannot quickly and accurately confirm the failure of therespective vehicles.

In this way, the number of vehicles which a conventional monitoringsystem can manage is limited because of the shortcomings of thecommunication system, even though it is necessary to exchange a largevolume of data.

With the foregoing in view, it is an object of the present invention toprovide means to perform communication over the whole region of a wideworking site without increasing cost due to the installation ofauxiliary equipment, and to sufficiently perform mutual control ofvehicles with a light burden on a monitoring station without sacrificingsafety, and to quickly and accurately confirm failures which occur totransmission/reception equipment, so that an abnormality can be dealtwith quickly and properly.

DISCLOSURE OF THE INVENTION

A first aspect of the present invention is a vehicle monitor comprisinga plurality of vehicles each having vehicle position measurement meansfor measuring an own vehicle position and a monitoring station whichtransmits command data to instruct traveling to the plurality ofvehicles, characterized in that first transmission/reception means fortransmitting/receiving at least the above command data between themonitoring station and the plurality of vehicles via a firstcommunication system which enables wireless communication over distancesbetween the monitoring station and the plurality of vehicles is providedin the monitoring station and the plurality of vehicles respectively,second transmission/reception means for transmitting/receiving positiondata measured by the above vehicle position measurement means betweenthe plurality of vehicles via a second communication system whichenables wireless communication over distances between the plurality ofvehicles and enables faster data transmission/reception than the firstcommunication system is provided in the plurality of vehiclesrespectively, and the respective vehicles judge the approach of othervehicles by transmitting the above position data between the pluralityof vehicles via the second transmission/reception means provided in theplurality of vehicles respectively, so that mutual positionrelationships between the plurality of vehicles are monitored.

According to the first aspect, the first communication/transmissionmeans (e.g. VHF, UHF system), enables communication over long distancesbetween the monitoring station and the plurality of vehicles withoutincreasing cost due to the installation of auxiliary equipment. Themonitoring station merely transmits at least the command data via thefirst transmission/reception means, and the position data istransmitted/received between the plurality of vehicles via the secondtransmission/reception means (e.g. SS wireless communication system) tomonitor the mutual position relationships between the plurality ofvehicles, therefore the frequency of communication between themonitoring station and the plurality of vehicles can be decreased, loadon the monitoring station and load on the communication lines can bedecreased, and collision prevention control can be performed byhigh-speed communication among the vehicles, which assures safety.

Also two types of transmission/reception means transmit data to thevehicles, so even if such an abnormality as a fault occurs in onetransmission/reception means, this information on the abnormality can beimmediately and accurately notified to the vehicles by the othertransmission/reception means so that predetermined abnormalityprocessing, stopping vehicles for example, is immediately and properlyexecuted.

A second aspect of the present invention is a vehicle monitor comprisinga plurality of vehicles each having vehicle position measurement meansfor measuring an own vehicle position and a monitoring station whichreceives position data transmitted from the respective vehicles, andtransmits command data to instruct traveling to the plurality ofvehicles while monitoring the mutual position relationships of theplurality of vehicles based on the received position data, characterizedin that first transmission/reception means for transmitting/receivingthe above position data and the above command data between themonitoring station and the plurality of vehicles via a firstcommunication system, which enables wireless communication overdistances between the monitoring station and the plurality of vehiclesis provided in the monitoring station and the plurality of vehiclesrespectively, second transmission/reception means fortransmitting/receiving the above position data between the plurality ofvehicles via a second communication system, which enables wirelesscommunication over the distances between the plurality of vehicles andenables faster data transmission/reception than the first communicationsystem, is provided in the plurality of vehicles respectively, the aboveposition data is transmitted to the monitoring station each time thepredetermined time elapses via the first transmission/reception meansprovided in the plurality of vehicles respectively, so that themonitoring station monitors the positions of the plurality of vehicles,and the respective vehicles judge the approach of other vehicles bytransmitting the above position data between the plurality of vehiclesvia the second transmission/reception means provided in the plurality ofvehicles respectively, so that the mutual position relationships betweenthe plurality of vehicles are monitored.

The second aspect of the invention has the following functions andeffects in addition to the functions and effects of the first aspect ofthe invention.

The position data is transmitted to the monitoring station each time thepredetermined time elapses via the first transmission/reception meansprovided in the plurality of vehicles respectively so that themonitoring station can monitor the positions of the plurality ofvehicles, therefore the monitoring station can know the general positionrelationships between the vehicles with a light load on thecommunication lines, and can accurately transmit appropriate commands toeach vehicle.

Also the position data is transmitted between the plurality of vehiclesvia the second transmission/reception means provided in the plurality ofvehicles respectively so that the respective vehicles judge the approachof other vehicles, therefore each vehicle can immediately and accuratelyknow the mutual position relationships between the vehicles, whichenables quick and accurate control to prevent collision between thevehicles when the vehicles are traveling a cross section or are passingeach other.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an external view of an unmanned dump truck monitoring system,which is an embodiment of the vehicle monitoring system in accordancewith the present invention;

FIG. 2 is a block diagram depicting the configuration of a communicationsystem of the embodiment;

FIG. 3 is a drawing depicting the state where the predeterminedtraveling path of an unmanned dump truck is divided into individualpoints in accordance with the embodiment;

FIG. 4 is a flow chart indicating failure judgment and abnormalityprocessing procedures in accordance with the present embodiment;

FIG. 5 is a flow chart indicating failure judgment and abnormalityprocessing procedures in accordance with the present embodiment;

FIG. 6 is a flow chart indicating failure judgment and abnormalityprocessing procedures in accordance with the present embodiment;

FIG. 7 is a flow chart indicating failure judgment and abnormalityprocessing procedures in accordance with the present embodiment; and

FIG. 8 is a drawing for explaining dead reckoning.

BEST MODE FOR CARRYING OUT THE INVENTION

Embodiments of the vehicle monitor in accordance with the presentinvention will now be described with reference to the accompanyingdrawings.

FIG. 1 is an external view of an unmanned dump truck monitoring systemwhich manages and monitors many unmanned dump trucks 10, 11, 12, 13, . .. in a wide working site 30, such as a mine, which is assumed in thisembodiment.

FIG. 2 is a block diagram depicting the wireless communication system ofthis unmanned dump truck monitoring system.

As FIG. 1 shows, this unmanned dump truck monitoring system comprises aplurality of unmanned dump trucks (hereafter vehicles) 10, 11, 12, 13, .. . having a later mentioned vehicle position measurement equipment formeasuring respective vehicle position (X, Y), and a monitoring station20 which receives the position data (X, Y) transmitted from theplurality of vehicles 10 . . . respectively, monitors the mutualposition relationship of the plurality of vehicles 10 . . . , andtransmits command data for instructing traveling and stopping to theplurality of vehicles 10 . . . based on the received position data.

In this embodiment, unmanned dump trucks are assumed as the vehicles,but the present embodiment may be applied to manned vehicles or suchvehicles other than dump trucks as wheel loaders and hydraulicexcavators, or a system where the unmanned vehicles and manned vehiclescoexist, or a system where dump trucks, wheel loaders, hydraulicexcavators and other vehicles coexist.

As FIG. 2 shows, wireless communication is performed between themonitoring station 20 and the plurality of vehicles 10 . . . viamonitoring station-vehicle communication equipment 23 and 5.

In the distances between the monitoring station 20 and the plurality ofvehicles 10 . . . , that is, in the whole region of the wide workingsite 30, communication systems which enable wireless communication, suchas the monitoring station-vehicle communication equipment 23 and 5 basedon the VHF system, are disposed in the monitoring station 20 and thevehicles 10 . . . respectively, and the above mentioned position dataand the command data are transmitted/received between the monitoringstation 20 and the plurality of vehicles 10 . . . .

The monitoring station-vehicle communication equipment 23 at themonitoring station 20 side comprises a transmission section 21 and areception section 22, and the monitoring station-vehicle communicationequipment 5 at the vehicle 10 side comprises a transmission section 1and a reception section 2, where wireless communication A is performedvia an antenna 20 a of the monitoring station 20 and an antenna 10 a ofthe vehicle 10, as shown in FIG. 1. For the other vehicles as well,wireless communication B is performed via the antenna 20 a of themonitoring station 20 and an antenna 11 a of the vehicle 11, wirelesscommunication C is performed via the antenna 20 a of the monitoringstation 20, and an antenna 12 a of the vehicle 12, and wirelesscommunication D is performed via the antenna 20 a of the monitoringstation 20 and an antenna 13 a of the vehicle 13 respectively in thesame manner.

Between the plurality of vehicles as well, wireless communication isperformed by the inter-vehicle communication equipment 6.

In other words, the inter-vehicle communication equipment 6, whichenables wireless communication over the distances between the pluralityof vehicles and enables faster data transmission/reception than theabove monitoring station-vehicle communication equipment 23 and 5, isdisposed in each vehicle 10, 11, 12, 13, . . . , and the above positiondata is transmitted/received between the plurality of vehicles.

The inter-vehicle communication equipment 6 of the vehicles 10 . . .comprises a transmission section 3 and a reception section 4, and asFIG. 1 shows, wireless communication E is performed via the antenna 10 bof the vehicle 10 and the antenna 11 b of the vehicle 11, wirelesscommunication F via the antenna 11 b of the vehicle 11 and the antenna12 b of the vehicle 12, wireless communication G via the antenna 10 b ofthe vehicle 10 and the antenna 12 b of the vehicle 12, wirelesscommunication H via the antenna 10 b of the vehicle 10 and the antenna13 b of the vehicle 13, and wireless communication I via the antenna 12b of the vehicle 12 and the antenna 13 b of the vehicle 13 respectively.Wireless communication may be impossible between vehicles where thedistance is greater than radio wave propagation distance (e.g. betweenvehicles 11 and 13).

A tire rotation sensor 30 (e.g. dial pulse encoder), which is a vehicletraveling distance detection part, is disposed on the tires of eachvehicle 10 . . . to detect rotation frequency N of tires. A gyro 31(e.g. optical fiber tyro), which is a vehicle orientation detectionsection, is disposed on the body of each vehicle to detect angular speedw of the posture angle of the vehicles.

The vehicle position (X, Y) (a position on 2-dimensional coordinatesystem X-Y) is detected based on each output of the above tire rotationsensor 30 and the gyro 31, as described later, but since this vehicleposition includes accumulated errors due to tire slippage and otherfactors, accumulated errors may be intermittently corrected by therelative position relationships between the vehicle and reflectionpoles, for example, which are disposed intermittently along thepredetermined traveling path of the vehicle.

The vehicle position may be measured by a GPS (Global PositioningSystem).

An arithmetic processing unit 32 comprised of a CPU, memory and othercomponents is equipped on each vehicle 10 . . . so that processing basedon later mentioned dead reckoning is performed, and control signals areoutput to e.g. each electromagnetic proportional control valve fordriving the vehicle.

The processing content to be executed by the arithmetic processing unit32 will now be explained.

When a detection signal of the tire rotation sensor 30, which is avehicle traveling distance detection part, and a detection signal of thegyro 31, which is a vehicle orientation detection part, are input to thearithmetic processing unit 32, the following processing is sequentiallyexecuted.

Operating vehicle traveling distance S

The tire rotation frequency N is determined based on the detectionsignal by the tire rotation sensor 30.

Then the vehicle traveling distance S is calculated by the product ofthe tire rotation frequency N and a known tire load radius r.

Operation of vehicle orientation θ

The change of vehicle orientation AO is calculated by integrating theangular speed ω posture angle of the vehicle based on the detectionsignal provided by the gyro 31, and the current vehicle orientation efrom the initial vehicle orientation is calculated by adding the changeof orientation Δθ to the known initial orientation.

Operation of vehicle position (X, Y)

The vehicle coordinate position (X, Y) on an X-Y coordinate isdetermined by integrating the product of the above vehicle travelingdistance S and sine sin and cosine cos of the vehicle orientation θ,which is S·sin θ, S·cos θ.

In other words, as FIG. 8 shows, sequential vehicle positions P1 (X1,Y1)=(S1·cos θ1, S1·sin θ1), P2 (X2, Y2)=(X1+S2·cos θ2, Y1+S2·sin θ2), .. . are calculated and locus 41 of each vehicle, vehicle 10 for example,is determined.

The arithmetic processing unit 32 compares the locus 41 of the vehicle10 which is computed as above, and the predetermined traveling path 40,which is a target route, and controls the vehicle 10 based on deadreckoning so that the vehicle 10 traces the predetermined travelingpath. In other words, the arithmetic processing unit 32 outputspredetermined electric signals to the steering hydraulic electromagneticproportional control valve and controls the steering angle of thesteering so that the sequential target vehicle positions P′1, P′2, P′3 .. . and the target vehicle orientations θ′1, θ′2, θ′3 . . . on thepredetermined traveling path 40 are obtained. The arithmetic processingunit 32 also outputs predetermined electric signals to an electroniccontrol governor, a transmission solenoid valve, and a brake pressureelectromagnetic proportional control valve so that the sequential targetvehicle positions and target vehicle orientations on the predeterminedtraveling path 40 are obtained, and controls the rotational frequency ofthe engine, speed steps of transmission and brake pressure. In this way,the vehicle 10 is guided so as to travel along the predeterminedtraveling path 40.

In this embodiment, many traveling paths 40-1, 40-2, 40-3 . . . areassumed as the predetermined traveling path 40, since the plurality ofvehicles 10 basically have different paths respectively. These travelingpaths 40-1, 40-2, 40-3 . . . may have cross points, and the vehicles maypass each other on the same traveling path.

Therefore, the teaching of such predetermined traveling path 40 isexecuted before actual operation.

Teaching traveling on predetermined traveling path 40

An operator actually operates one vehicle, vehicle 10 for example,allowing it to travel along all the predetermined traveling paths 40-1,40-2, 40-3 . . . to obtain the position data (X, Y) and orientation dataθ′ of each point P′1, P′2, P′3 . . . on the predetermined travelingpaths, data on speed when passing each point, and other data (hereaftertraveling path data), and the traveling path data is transmitted to themonitoring station 20 by the above mentioned monitoring station-vehiclecommunication equipment 5.

The monitoring station 20, which received this traveling path data,transmits the traveling path data on the predetermined traveling pathsrequired for each vehicle 10, 11, 12, 13 . . . to each vehicle by themonitoring station-vehicle communication equipment 23. If thepredetermined traveling path of the vehicle 10 is the traveling path40-1, for example, the traveling path data on the traveling path 40-1 istransmitted to the vehicle 10. All traveling path data may betransmitted to each vehicle.

During this teaching, the dividing position data (X, Y) of each dividingpoint Q1, Q2, Q3 . . . , when the predetermined traveling path 40 isdivided into a plurality of points, is obtained separately from thetarget points for dead reckoning (see FIG. 3).

Each time a respective vehicle passes each one of these dividing pointsQ1, Q2, Q3, the respective vehicle is supposed to transmit the currentposition data P (X, Y) of the respective vehicle to the monitoringstation 20 via the monitoring station-vehicle communication equipment 5.Therefore the following is considered when these dividing points Q1, Q2,Q3 . . . are defined.

1) Considering the number of vehicles and the communication speed of thecommunication system (e.g. VHF) of the monitoring station-vehiclecommunication equipment 23 and 5, an interval (time) is set such that aheavy load is not applied to the communication line and the monitoringstation 20 can constantly know the position of each vehicle.

The following can also be considered.

2) Considering the weight and speed of the vehicle, the dividing pointsare set such that the distance between adjacent dividing points(Qi−Qi+1) is not shorter than the stopping distance of the vehicle.

3) The dividing points are set such that when an obstacle sensor isdisposed on the vehicle, the distance between the adjacent dividingpoints (Qi−Qi+1) is not shorter than the effective detection distance ofthe obstacle sensor.

The dividing point data obtained in this way is transmitted to themonitoring station 20 along with the above traveling path data via themonitoring station-vehicle communication equipment. 5.

The monitoring station 20 receives this dividing point data andtransmits the dividing point data on the predetermined traveling pathsrequired for the vehicle 10, 11, 12, 13 . . . to these vehiclesrespectively via the monitoring station-vehicle communication equipment23. For example, if the predetermined traveling path of the vehicle 10is the traveling path 40-1, then the dividing point data on thetraveling path 40-1 is transmitted to the vehicle 10. The dividing pointdata on all the traveling paths may be transmitted to each vehicle.

Teaching ends in this way and teaching data (traveling path data,dividing point data) is stored in the predetermined memory of eachvehicle.

In the above embodiment, dividing points are defined as points whereeach vehicle transmits current position data P (X, Y) of that respectivevehicle to the monitoring station 20, but the interval of thetransmission time, equivalent to the distance between the dividingpoints, may be preset. To determine the interval of the transmissiontime as well, the above 1), 2) and 3) (at least 1)) are considered.

Starting traveling of each vehicle (playback operation)

When the above mentioned teaching ends, the monitoring station 20transmits the command data indicating the final target position(destination) to each vehicle 10 . . . via the transmission section 21of the monitoring station-vehicle communication equipment 23. Ifposition measurement is performed by GPS, the monitoring station 20transmits the differential data of GPS to the respective vehicles.

When the reception section 2 of the monitoring station-vehiclecommunication equipment 5 of each vehicle receives the above data, thearithmetic processing unit 32 guides the respective vehicle along thepredetermined traveling path 40 by the above mentioned dead reckoningbased on the teaching traveling path data stored in the memory, andexecutes a series of operations such as loading, transporting andunloading.

Controlling and monitoring by the monitoring station

During the above time, each vehicle 10 . . . constantly compares itscurrent position measuring data (X, Y) and the teaching data on dividingpoints stored in its memory, and constantly judges whether therespective vehicle has reached each dividing point Q1, Q2 and Q3. Whenthe vehicle reaches a dividing point, the transmission part 1 of themonitoring station-vehicle communication equipment 5 transmits thecurrent position data (X, Y) to the monitoring station 20.

When the reception section 22 of the monitoring station-vehiclecommunication equipment 23 of the monitoring station 20 receives theposition data which was transmitted by the respective vehicles 10 . . ., the arithmetic processing unit 24 of the monitoring station 20 judgesthat the plurality of vehicles 10 . . . approached at least a distancebetween the dividing points Qi−Qi+1 (hereafter segment).

In this way, the monitoring station 20 can constantly know the generalmutual position relationships between the plurality of vehicles withoutapplying load on the communication lines, and as a result, when vehiclesare about to collide with each other at a cross section or when avehicle is about to bump into another vehicle, appropriate command datafor traveling and stopping can be transmitted to the vehicles via thetransmission section 21 of the monitoring station-vehicle communicationequipment 23.

In the situation shown in FIG. 3, for example, the vehicle 10 istraveling a segment between the dividing points Q2-Q3, and the vehicle11 is traveling a segment between the dividing points Q103-Q5, where thevehicles have a sufficient distance in between and do not collide at thecross section, therefore the vehicles can continuously travel, but ifthe vehicle 10 is traveling the dividing points Q3-Q4, the distancebetween the vehicles is not sufficient and a collision may occur at thecross section, therefore the command data for decreasing speed or forstopping is transmitted to the vehicle 10.

In the above mentioned embodiment, each vehicle 10 . . . transmits thecurrent position data to the monitoring station 20, but the orientationdata θ, speed data, data indicting the reliability (error) of positionmeasurement, and data indicating the deviation of the vehicle from thepredetermined traveling path 40, and other data, may also be transmittedto the monitoring station 20 so as to improve the accuracy of controland monitoring of the monitoring station 20.

Control and monitoring between vehicles

When the respective vehicles 10 . . . are traveling (operating), theposition data is transmitted/received between the vehicles via theinter-vehicle communication equipment 6 disposed in the respectivevehicles.

Since communication lines may Jam if all the vehicles transmit/receiveat the same time, priority can be determined as follows.

1) Respective vehicles constantly transmit the position data of therespective vehicles via the inter-vehicle communication equipment 6, bywhich respective vehicles confirm the presence of the vehicles travelingwithin the closest distance. Hereafter, the vehicles closest to eachother frequently transmit/receive the position data via theinter-vehicle communication equipment 6 with priority.

2) The monitoring station 20 confirms the presence of vehicles closestto each other based on the position data transmitted from the respectivevehicles. The monitoring station 20 transmits this information to thosevehicles closest to each other via the monitoring station-vehiclecommunication equipment 23 and 5. Hereafter, the vehicles closest toeach other, to which this information was transmitted, frequentlytransmit/receive the position data via the inter-vehicle communicationequipment 6 with priority.

The vehicles which are assigned priority in inter-vehicle communicationperform control so as to prevent the mutual interference of the vehiclesbased on the received position data of the other vehicle.

In other words, when the vehicles are about to collide at a crosssection or when one vehicle is about to bump into another vehicle, it isdecided which vehicle will decrease speed and which vehicle willadvance.

Although the monitoring station 20 can only judge that the respectivevehicles 10 . . . have approached a distance between dividing pointsQi−Qi+1 (hereafter segment), as described above (can judge thatdifferent vehicles are traveling the same segment), the inter-vehiclecommunication equipment 6 allows the respective vehicles to accuratelyjudge that another vehicle has approached a shorter distance than theabove segment distance.

As a result, control when vehicles closely approach each other, asituation where the monitoring station 20 cannot instruct, is possibleto prevent interference when vehicles pass each other. When the vehicles10 and 11 in FIG. 3 are traveling towards each other in the same segmentQ2-Q3, for example, both of the vehicles 10 and 11 know the accuratepositions in the segment Q2-Q3, so it is possible to accurately avoideach other by traveling at a minimum decrease in speed when they passeach other.

In the above embodiment, the respective vehicles 10 . . .transmit/receive their current positions to each other via theinter-vehicle communication equipment 6, but orientation data θ, speeddata, data indicating reliability (error) of position measurement, dataindicating deviation of a vehicle from the predetermined traveling path40, data indicating the weight of the vehicle, and data indicating thedistance to a cross section may be transmitted/received as well so as toimprove the accuracy of priority when entering a cross section andaccuracy to prevent a collision. Also in addition to the position data,orientation data θ, speed data, data indicating reliability (error) ofposition measurement, data indicating deviation of the vehicle from thepredetermined traveling path 40, and data indicating the weight of thevehicle, data indicating the effective detection distance of theobstacle detection sensor may be transmitted/received so as to improvethe accuracy of speed to be decreased when vehicles pass each other byand to improve the accuracy to prevent a collision.

Handling at communication equipment failure

In this embodiment, data can be transmitted to vehicles by the twocommunication equipment, therefore, even if an abnormality, such as afailure, occurs to one communication equipment, the information on theoccurrence of an abnormality can be immediately and accurately notifiedto the vehicles via the other communication equipment, so as toimmediately and properly execute predetermined abnormality processing,such as stopping vehicles.

FIG. 4 is a flow chart indicating the failure judgment and abnormalityprocessing procedures when the monitoring station 20 cannot transmitdata to the vehicles.

The monitoring station 20 transmits predetermined data, data indicatingthe mutual position relationships of all the vehicles for example, tothe respective vehicles 10 . . . via the transmission section 21 of themonitoring station-vehicle communication equipment 23 at a predeterminedcycle. The respective vehicles 10. . . , on the other hand, judgewhether the reception part 2 of the monitoring station-vehiclecommunication equipment 5 of the respective vehicle received the abovepredetermined data each time the above predetermined cycle elapses. Andif the vehicle 10, for example, judges that the above predetermineddata, which was supposed to have been transmitted from the monitoringstation 20, has not been received (Step 101), then the vehicle 10 judgesthat a failure occurred either to the transmission section 21 of themonitoring station-vehicle communication equipment 23 of the monitoringstation 20 or to the reception section 2 of the monitoringstation-vehicle communication equipment 5 of the vehicle 10, and thevehicle 10 stops to insure safety judging that sufficient information toprevent a collision of vehicles cannot be obtained in this state (Step102).

The stopped vehicle 10 executes transmission/reception with the othervehicles 11, 12 . . . which are nearby via the inter-vehiclecommunication equipment 6 which is functioning normally, so as toconfirm the reception state of the other vehicles with the monitoringstation 20 (Step 103).

The other vehicles 11, 12 . . . judge whether the above predetermineddata has been received via the reception section 2 of own monitoringstation-vehicle communication equipment 5 each time the abovepredetermined cycle elapses (Step 104), and if the other vehicles Judgethat the above predetermined data, which was supposed to have beentransmitted from the monitoring station 20, has not been received aswell, then the vehicle 10 judges that a failure occurred to thetransmission section 21 of the monitoring station-vehicle communicationequipment 23 of the monitoring station 20 (the reception section 2 ofthe monitoring station-vehicle communication equipment 5 of the vehicle10 is normal) (Step 105), and transmits the failure occurrence dataindicating the ‘failure of the transmission section of the monitoringstation’ to the monitoring station 20. This failure occurrence data orthe normality confirmation data indicating the normality of thetransmission section is periodically (e.g. along with the abovementioned position data) transmitted from the vehicles to the monitoringstation 20 (Step 106).

If the vehicle 10 judges that the other vehicles received the abovepredetermined data, which was supposed to have been transmitted from themonitoring station 20 in Step 104, on the other hand, then the vehicle10 judges that a failure occurred to the reception part 2 of themonitoring station-vehicle communication equipment 5 of own vehicle 10(the transmission section 21 of the monitoring station-vehiclecommunication equipment 23 of the monitoring station 20 is normal) (Step110), and transmits failure occurrence data indicating the ‘failure ofthe reception section of the vehicle 10’ to the monitoring station 20(Step 111).

FIG. 5 is a flow chart indicating the failure Judgment and abnormalityprocessing procedures when data is not transmitted from a vehicle to themonitoring station 20.

The monitoring station 20 sequentially judges whether the position dataP is received each time the above mentioned predetermined time, wheneach vehicles pass the dividing point Q elapses.

If the periodical transmission of the position data P from a vehiclestops as the result of the judgment (Step 201), then the monitoringstation 20 judges whether transmission from all the vehicles 10 . . .stopped (Step 202).

If the monitoring station 20 judges that the position data which issupposed to have been transmitted from a specific vehicle, the vehicle10 for example, has not been received and that the position datatransmitted from the other vehicles 11, 12 . . . has been received, thenthe monitoring station 20 judges that a failure occurred to thetransmission section 1 of the monitoring station-vehicle communicationequipment 5 of the vehicle 10 and confirms this judgment (Steps 203,204). Then the monitoring station 20 transmits the command dataindicating that ‘a failure occurred to the transmission section of thevehicle 10, the vehicle 10 must stop’ to a vehicle near the vehicle 10,the vehicle 11 for example (Step 205). The vehicle 11 receives thiscommand data, and transmits this command data to the vehicle 10 where afailure occurred via the inter-vehicle communication equipment 6 (Step206). The vehicle 10 receives this command data by the reception section4 of its inter-vehicle communication equipment 6 which is operatingnormally, judges that ‘the monitoring station 20 cannot know the currentposition of the vehicle 10 in this state, and sufficient information toavoid a collision of vehicles cannot be obtained’, and the vehicle 10stops to insure safety (Step 207).

After the monitoring station 20 judges that a failure occurred to thetransmission section 1 of the monitoring station-vehicle communicationequipment 5 of the vehicle 10 and confirmed this information in Steps203 and 204, the monitoring station 20 transmits the failure occurrencedata indicating the ‘failure of the transmission section of the vehicle10’ to the vehicle 10. This failure occurrence data or the normalityconfirmation data indicating the normality of the transmission sectionis periodically transmitted from the monitoring station 20 to thevehicles (Step 208). Then the vehicle 10 stops (Step 207).

If, on the other hand, the monitoring station 20 judges that theposition data was not received from all the vehicles 10 . . . in Step202, then the monitoring station 20 judges that a failure occurred tothe reception section 22 of the monitoring station-vehicle communicationequipment 23 of the monitoring station 20 (the transmission section 1 ofthe monitoring station-vehicle communication equipment 5 of the vehicleis normal) (Step 211), confirms this judgment (Step 212) then transmitsthe failure occurrence data indicating the ‘failure of the receptionsection of the monitoring station 20’ to all the vehicles (Step 213).The respective vehicles which received this failure occurrence datajudge that the monitoring station 20 cannot know the current positionsof all the vehicles in this state, and the vehicles stop to insuresafety judging that sufficient information to avoid a collision ofvehicles cannot be obtained (Step 214).

FIG. 6 is a flow chart indicating the failure judgment and abnormalityprocessing procedures when the data cannot be transmitted betweenvehicles.

The monitoring station 20 transmits data indicating the mutual positionrelationships of all the vehicles via the transmission section 21 of themonitoring station-vehicle communication equipment 23 to the respectivevehicles 10 . . . at a predetermined cycle. The respective vehicles 10 .. . , on the other hand, judge whether other vehicles are present withinthe communication distance of the inter-vehicle communication equipment6 based on the above position relationship data (Steps 301 and 302).

If the vehicle 10, for example, judges that another vehicle, the vehicle11, is present in the communication area, the vehicle 10transmits/receives the position data to/from the vehicle 11 via theinter-vehicle communication equipment 6, and the vehicle 10 confirms thereception state (Steps 303 and 304). If the vehicle 10 cannot receivethe position data from the vehicle 11 at this time (NO in Step 304),then the vehicle 10 judges that a failure occurred to at least thereception section 4 of the inter-vehicle communication equipment 6 ofthe vehicle 10, and executes abnormality processing, such as stoppingthe vehicle 10 (Step 306). If the vehicle 10 receives the position datafrom another vehicle, vehicle 11 (YES in Step 304), then the vehicle 10confirms that the inter-vehicle communication equipment 6 of the vehicle10 is normal (Step 305).

FIG. 7 is a flow chart indicating the failure judgment and abnormalityprocessing procedures when data cannot be transmitted between vehicles.

A respective vehicle, the vehicle 10 for example, judges whether theposition data has been transmitted from other vehicles 11, 12 . . . viathe inter-vehicle communication equipment 6 each time a predeterminedtime elapses. This predetermined time has been set to a maximum time inwhich other vehicles can transmit the position data (Step 401) if theother vehicles are present within a communication distance of theinter-vehicle communication equipment 6.

If the vehicle 10 has not received the position data from other vehicles11, 12 . . . after the above predetermined time elapses, then thevehicle 10 transmits information that the position data has not beenreceived, and information to inquire ‘whether another vehicle which cancommunicate via the inter-vehicle communication equipment 6 is presentnear the vehicle 10’ is transmitted to the monitoring station 20 via themonitoring station-vehicle communication equipment 5 (Step 404).

The monitoring station 20 judges whether another vehicle is presentwithin the communication distance of the inter-vehicle communicationequipment 6 for the vehicle 10 which transmitted the above information,and if it is judged that another vehicle is present, then the monitoringstation 20 judges that a failure occurred to the reception part 4 of theinter-vehicle communication equipment 6 of the vehicle 10 which sent theabove information (Step 406).

Then the monitoring station 20 transmits the command data to stop thevehicle 10 to which a failure occurred to insure safety (Step 407), andthe vehicle 10 which received this data stops and notifies the stoppingto the monitoring station 20 (Step 408).

As a result of the inquiry in Step 404, it is judged that no vehiclesare present within communication distance of the inter-vehiclecommunication equipment 6 for the vehicle 10, then the monitoringstation 20 judges that the inter-vehicle communication equipment 6 ofthe vehicle 10 which transmitted the above information is normal (Step405).

If the vehicle 10 received the position data from other vehicles 11, 12. . . before the above predetermined time elapses in the above Step 401,then the vehicle 10 requests the other vehicle which transmitted thisposition data, the vehicle 11 for example, to transmit the position dataof the vehicle 10 via the inter-vehicle communication equipment 6 (Step402).

If the other vehicle 11 transmits the position of the vehicle 10 to thevehicle 10 via the inter-vehicle communication equipment 6 in responseto the request, the vehicle 10 judges and confirms that the functions ofthe inter-vehicle communication equipment 6 are normal (Step 403).

If the other vehicle 11 does not transmit the position data of thevehicle 10 to the vehicle 10 via the inter-vehicle communicationequipment 6 in response to the request in the above step 402, then thevehicle 10 judges that a failure occurred to the transmission section 3of the inter-vehicle communication equipment 6 (Step 409), the vehicle10 stops to insure safety (Step 410), and notifies the stopping to themonitoring station 20 (Step 411).

In the present embodiment, the respective vehicles transmit the positiondata to the monitoring station 20 at a predetermined interval, so thatthe monitoring station knows the general position relationships of theplurality of vehicles, but this process may be omitted and the functionsof the monitoring station 20 may be limited only to instructing adestination to each vehicle (traveling instruction) where grasp of themutual position relationships of the vehicles is left to theinter-vehicle communication.

The abnormality of at least the transmission section 21 of themonitoring station-vehicle communication equipment 23 of the vehicle 10may be judged as follows.

1) Each one of the vehicle 10, 11, 12 . . . transmits the speed data ofthe vehicle each time the vehicle reaches the traveling points Q1, Q2 .. . of the traveling path 40.

2) Based on the transmitted speed data, the monitoring station 20estimates the time required to allow for the vehicles 10, 11, 12 . . .to pass the next dividing point. If the position data which the vehicle10 is supposed to have transmitted has not been received when thisestimate time occurs, the monitoring station 20 judges that at least thetransmission section 21 of the monitoring station-vehicle communicationequipment 23 of the vehicle 10 has an abnormality.

Industrial Applicability

The present invention can be applied not only to vehicles travelingoutdoors but to vehicles traveling indoors as well. For example, thepresent invention can be applied to the automatic carrier system in afactory.

What is claimed is:
 1. A vehicle monitor comprising a plurality ofvehicles each having vehicle position measurement means for measuring anown vehicle position and a monitoring station which transmits commanddata to instruct traveling to the plurality of vehicles, characterizedin that: first transmission/reception means for transmitting/receivingat least the command data between the monitoring station and theplurality of vehicles via a first communication system which enableswireless communication over distances between the monitoring station andthe plurality of vehicles is provided in the monitoring station and theplurality of vehicles respectively, second transmission/reception meansfor transmitting/receiving position data measured by the vehicleposition measurement means between the plurality of vehicles via asecond communication system which enables wireless communication overdistances between the plurality of vehicles and enables faster datatransmission/reception than the first communication system is providedin the plurality of vehicles respectively, and the respective vehiclesjudge the approach of other vehicles by transmitting the position databetween the plurality of vehicles via the second transmission/receptionmeans provided in the plurality of vehicles respectively, so that mutualposition relationships between the plurality of vehicles are monitored.2. The vehicle monitor according to claim 1, characterized in that whendata has not been input from other vehicles via the secondtransmission/reception means after the predetermined time elapses, theplurality of vehicles respectively transmit this information to themonitoring station via the first transmission/reception means, themonitoring station judges that another vehicle is present within acommunication distance of the second transmission/reception means forthe vehicle which transmitted the information, and in the case when thisjudgment is made, the respective vehicles judge that at least receptionmeans of the second transmission/reception means of the vehicle whichtransmitted the information has an abnormality.
 3. The vehicle monitoraccording to claim 1, characterized in that the monitoring stationtransmits predetermined data to the plurality of vehicles each time apredetermined time elapses, the plurality of vehicles judge whether thepredetermined data has been received each time the predetermined timeelapses, and in the case when it is judged that the predetermined datawhich is supposed to have been transmitted from the monitoring stationhas not been received, the respective vehicles judge that the firsttransmission/reception means has an abnormality and executespredetermined abnormality processing.
 4. The vehicle monitor accordingto claim 1, characterized in that the plurality of vehicles respectivelytransmit own position data constantly to other vehicles via the secondtransmission/reception means, by which respective vehicles confirm thepresence of a vehicle closest to own vehicle, and the position data istransmitted/received between the vehicles closest to each other via thesecond transmission/reception means, so as to perform control to preventmutual interference of the vehicles closest to each other.
 5. A vehiclemonitor comprising a plurality of vehicles each having vehicle positionmeasurement means for measuring an own vehicle position and a monitoringstation which receives position data transmitted from the respectivevehicles and transmits command data to instruct traveling to theplurality of vehicles while monitoring mutual position relationships ofthe plurality of vehicles based on the received position data,characterized in that: first transmission/reception means fortransmitting/receiving the position data and the command data betweenthe monitoring station and the plurality of vehicles via a firstcommunication system which enables wireless communication over distancesbetween the monitoring station and the plurality of vehicles is providedin the monitoring station and the plurality of vehicles respectively,second transmission/reception means for transmitting/receiving theposition data between the plurality of vehicles via a secondcommunication system which enables wireless communication over distancesbetween the plurality of vehicles and enables faster datatransmission/reception than the first communication system, is providedin the plurality of vehicles respectively, the position data istransmitted to the monitoring station each time predetermined timeelapses via the first transmission/reception means provided in theplurality of vehicles respectively, so that the monitoring stationmonitors the positions of the plurality of vehicles, and the respectivevehicles Judge the approach of other vehicles by transmitting theposition data between the plurality of vehicles via the secondtransmission/reception means provided in the plurality of vehiclesrespectively, so that the mutual position relationships between theplurality of vehicles are monitored.
 6. The vehicle monitor according toclaim 5, characterized in that a predetermined traveling path where thevehicles travel is divided, and the vehicles transmit the position datato the monitoring station each time the vehicles reach each dividingpoint.
 7. The monitoring station according to claim 6, characterized inthat the plurality of vehicles respectively transmit speed data of thevehicle to the monitoring station each time the vehicles reach thedividing point, and the monitoring station estimates a time required forthe vehicle to pass a next dividing point based on the speed data, andin the case when the position data which is supposed to have beentransmitted from the vehicle has not been received when the estimatedtime elapsed, the monitoring station judges that at least thetransmission means of the first transmission/reception means of thevehicle has an abnormality.
 8. The vehicle monitor according to claim 5,characterized in that the monitoring station judges whether the positiondata has been received each time the predetermined time elapses, and inthe case when the position data which is supposed to have beentransmitted from a specific vehicle has not been received and positiondata transmitted from other vehicles has been received as a result ofthe judgment, the monitoring station judges that at least the firsttransmission/reception means of the specific vehicle has an abnormalityand transmits this information to the other vehicles via the firsttransmission/reception means, the other vehicles transmit thisinformation to the specific vehicle via the secondtransmission/reception means, and the specific vehicle which receivedthis information on the abnormality executes predetermined abnormalityprocessing.
 9. The vehicle monitor according to claim 5, characterizedin that the plurality of vehicles respectively judge that anothervehicle is present within a communication distance of the secondtransmission/reception means based on the position information of eachvehicle transmitted from the monitoring station via the firsttransmission/reception means, and in the case when this judgment is madeand the position data has not been received from the other vehicle viathe second transmission/reception means, the respective vehicles judgethat at least reception means of the second transmission/reception meansof own vehicle has an abnormality and executes predetermined abnormalityprocessing.
 10. The vehicle monitor according to claim 5, characterizedin that the monitoring station confirms the presence of vehicles closestto each other based on the position data transmitted from the pluralityof vehicles via the first transmission/reception means and transmitsthis information to the vehicles closest to each other via the firsttransmission/reception means, and the vehicles closest to each other towhich this information is transmitted transmit/receive the position databetween the vehicles closest to each other via the secondtransmission/reception means, so as to perform control to prevent mutualinterference of the vehicles closest to each other.
 11. The vehiclemonitor according to claim 5, characterized in that when data has notbeen input from other vehicles via the second transmission/receptionmeans after the predetermined time elapses, the plurality of vehiclesrespectively transmit this information to the monitoring station via thefirst transmission/reception means, the monitoring station judges thatanother vehicle is present within a communication distance of the secondtransmission/reception means for the vehicle which transmitted theinformation, and in the case when this judgement is made, the respectivevehicles judge that at least reception means of the secondtransmission/reception means of the vehicle which transmitted theinformation has an abnormality.
 12. The vehicle monitor according toclaim 5, characterized in that the monitoring station transmitspredetermined data to the plurality of vehicles each time apredetermined time elapses, the plurality of vehicles judge whether thepredetermined data has been received each time the predetermined timeelapses, and in the case when it is judged that the predetermined datawhich is supposed to have been transmitted from the monitoring stationhas not been received, the respective vehicles judge that the firsttransmission/reception means has an abnormality and executespredetermined abnormality processing.
 13. The vehicle monitor accordingto claim 5, characterized in that the plurality of vehicles respectivelytransmit own position data constantly to other vehicles via the secondtransmission/reception means, by which respective vehicles confirm thepresence of a vehicle closest to own vehicle, and the position data istransmitted/received between the vehicles closest to each other via thesecond transmission/reception means, so as to perform control to preventmutual interference of the vehicles closest to each other.